Metastable beta-titanium alloys and methods of processing the same by direct aging

• US 10,422,027 B2
• Filed: 11/10/2016
• Issued: 09/24/2019
• Est. Priority Date: 05/21/2004
• Status: Active Grant

• Current Assignee: ATI Properties LLC
• Original Assignee: ATI Properties LLC
• Inventors: Marquardt, Brian, Wood, John Randolph, Freese, Howard L., Jablokov, Victor R.
• Primary Examiner(s): Roe, Jessee R
• Application Number:
  US15/348,140
• Publication Number:
  US 20170058387A1
• Time in Patent Office: 1,048 Days
• CPC Class Codes: C22C 14/00 Alloys based on titanium
• CPC Class Codes: C22F 1/183 of titanium or alloys based thereon

Abstract

Metastable beta titanium alloys and methods of processing metastable β-titanium alloys are disclosed. For example, certain non-limiting embodiments relate to metastable β-titanium alloys, such as binary β-titanium alloys comprising greater than 10 weight percent molybdenum, having tensile strengths of at least 150 ksi and elongations of at least 12 percent. Other non-limiting embodiments relate to methods of processing metastable β-titanium alloys, and more specifically, methods of processing binary β-titanium alloys comprising greater than 10 weight percent molybdenum, wherein the method comprises hot working and aging the metastable β-titanium alloy at a temperature below the β-transus temperature of the metastable β-titanium alloy for a time sufficient to form α-phase precipitates in the metastable β-titanium alloy. The metastable β-titanium alloys are not solution heat treated after hot working and prior to aging. Articles of manufacture comprising binary β-titanium alloys according to various non-limiting embodiments disclosed herein are also disclosed.

Claims

1. A method of processing a binary β

-titanium alloy, the method-comprising;

hot working a binary β

-titanium alloy consisting essentially of titanium, greater than 10 weight percent molybdenum, and incidental impurities; and

heating the binary β

-titanium alloy within an aging temperature range from 850°

F. to 1375°

F. for a time sufficient to form α

-phase precipitates within the binary β

-titanium alloy;

wherein the binary β

-titanium alloy is not solution heat treated after hot working and prior to heating within the aging temperature range.

2. The method of claim 1, wherein the binary β

-titanium alloy consists essentially of titanium, 14 to 16 weight percent molybdenum, and incidental impurities.

3. The method of claim 1, wherein hot working the binary β

-titanium alloy comprises at least one of hot rolling, hot extruding, hot forging, and hot drawing.

4. The method of claim 1, wherein hot working the binary β

-titanium alloy comprises hot working to a reduction in area of at least 75 percent.

5. The method of claim 1, wherein the aging temperature range is from greater than 900°

F. up to 1200°

F.

6. The method of claim 1, wherein the aging temperature range is from 925°

F. to 1150°

F.

7. The method of claim 1, wherein the aging temperature range is from 950°

F. to 1100°

F.

8. The method of claim 1, wherein prior to hot working the binary β

-titanium alloy, the binary β

-titanium alloy is produced by a process comprising at least one of plasma arc cold hearth melting and vacuum arc remelting.

9. The method of claim 1, wherein subsequent to heating the binary β

-titanium, the binary β

-titanium alloy has a tensile strength of at least 180 ksi.

10. The method of claim 1, wherein subsequent to heating the binary β

-titanium, the binary β

-titanium alloy has a tensile strength of at least 150 ksi and an elongation of at least 12 percent.

11. The method of claim 1, wherein the time for heating is in a range of 0.5 to 5 hours.

12. A method of processing a binary β

-titanium alloy, the method comprising;

hot working a binary β

-titanium alloy consisting essentially of titanium, greater than 10 weight percent molybdenum, and incidental impurities;

heating the binary β

-titanium alloy at a first aging temperature below a β

-transus temperature of the binary β

-titanium alloy for a time sufficient to form and at least partially coarsen at least one α

-phase precipitate within at least a portion of the binary β

-titanium alloy; and

subsequently

heating the binary β

-titanium alloy at a second aging temperature that is lower than the first aging temperature for a time sufficient to form at least one additional α

-phase precipitate within at least a portion of the binary β

-titanium alloy;

wherein the binary β

-titanium alloy is not solution heat treated Intermediate hot working the binary β

-titanium alloy and heating the binary β

-titanium alloy at the first aging temperature.

13. The method of claim 12, wherein the binary β

-titanium alloy consists essentially of titanium, 14 to 16 weight percent molybdenum, and incidental impurities.

14. The method of claim 12, wherein hot working the binary β

-titanium alloy comprises at least one of hot rolling, hot extruding, hot forging, and hot drawing.

15. The method of claim 12, wherein hot working the binary β

-titanium alloy comprises hot working the binary β

-titanium alloy to a reduction in area of at least 75 percent.

16. The method of claim 12, wherein the first aging temperature is in a range of 1225°

F. to 1375°

F.

17. The method of claim 12, wherein the first aging temperature in a range of 1250°

F. to 1350°

F.

18. The method of claim 12, wherein the first aging temperature is in a range of 1275°

F. to 1325°

F.

19. The method of claim 12, wherein the first aging temperature is in a range of 1275°

F. to 1300°

F.

20. The method of claim 12, wherein the second aging temperature is in a range of 850°

F. to 1000°

F.

21. The method of claim 12, wherein the second aging temperature is in a range of 875°

F. to 1000°

F.

22. The method of claim 12, wherein the second aging temperature is in a range of 900°

F. to 1000°

F.

23. The method of claim 12, wherein:

prior to heating the binary β

-titanium alloy at the first aging temperature, the binary β

-titanium alloy has a microstructure comprising metastable phase regions;

heating the binary β

-titanium alloy at the first aging temperature comprises heating the binary β

-titanium alloy for a time sufficient to form and at least partially coarsen α

-phase precipitates within some metastable phase regions of the binary β

-titanium alloy; and

heating the binary β

-titanium alloy at the second aging temperature comprises heating the binary β

-titanium alloy for a time sufficient to form α

-phase precipitates within a majority of remaining metastable phase regions in the binary β

-titanium alloy.

24. The method of claim 23, wherein heating the binary β

-titanium alloy at the second aging temperature comprises heating the binary β

-titanium alloy for a time sufficient to form α

-phase precipitates within essentially all of the remaining metastable phase regions in the binary β

-titanium alloy.

25. The method of claim 12, wherein subsequent to heating the binary β

-titanium alloy at the second aging temperature, the binary β

-titanium alloy has a microstructure comprising at least one coarse α

-phase precipitate and at least one fine α

-phase precipitate.

26. The method of claim 12, wherein subsequent to heating the binary β

-titanium alloy at the second aging temperature, the binary β

-titanium alloy has a tensile strength of at least 150 ksi.

27. The method of claim 12, wherein subsequent to heating the binary β

-titanium alloy at the second aging temperature, the binary β

-titanium alloy has a tensile strength of at least 170 ksi.

28. The method of claim 12, wherein subsequent to heating the binary β

-titanium alloy at the second aging temperature, the binary β

-titanium alloy has a tensile strength of at least 180 ksi.

29. The method of claim 12, wherein subsequent to heating the binary β

-titanium alloy at the second aging temperature, the binary β

-titanium alloy has an elongation of at least 12 percent.

30. The method of claim 12, wherein subsequent to heating the binary β

-titanium alloy at the second aging temperature, the binary β

-titanium alloy has an elongation of at least 15 percent.

31. The method of claim 12, wherein subsequent to heating the binary β

-titanium alloy at the second aging temperature, the binary β

-titanium alloy has an elongation of at least 20 percent.

32. The method claim 12, wherein subsequent to heating the binary β

-titanium alloy in the hot worked condition at the aging temperature, the binary β

-titanium alloy has a tensile strength of 150 ksi to 180 ksi and an elongation of 12 to 20 percent.

33. The method of claim 12, wherein subsequent to heating the binary β

-titanium alloy at the second aging temperature, the binary β

-titanium alloy has a rotating beam fatigue strength of at least 550 MPa.

34. The method of claim 12, wherein subsequent to heating the binary β

-titanium alloy at the second aging temperature, the binary β

-titanium alloy has a rotating beam fatigue strength of at least 650 MPa.

35. The method of claim 12, wherein prior to hot working the binary β

-titanium alloy, the binary β

-titanium alloy is produced by a process comprising at least one of plasma arc cold hearth melting and vacuum arc remelting.

36. The method of claim 12, wherein the time for heating at the first aging temperature is in a range of 0.5 to 5 hours.

37. The method of claim 12, wherein the time for heating at the second aging temperature is in a range of 0.5 to 5 hours.

38. A method of processing a binary β

-titanium alloy, the method comprising;

hot working the binary β

-titanium alloy to a reduction in area of at least 95 percent by at least one of hot rolling, hot extruding, hot forging, and hot drawing the binary β

-titanium alloy; and

heating the binary β

-titanium alloy at an aging temperature below the β

-transus temperature of the binary β

-titanium alloy for a time sufficient to form α

-phase precipitates within the binary β

-titanium alloy;

wherein the binary β

-titanium alloy is not solution heat treated intermediate hot working the binary β

-titanium alloy and heating the binary β

-titanium alloy at the aging temperature.

39. A method of processing a binary β

-titanium alloy, the method comprising;

hot working a binary β

-titanium alloy comprising greater than 10 weight percent molybdenum; and

heating the binary β

-titanium alloy in the hot worked condition at an aging temperature below the β

-transus temperature of the binary β

-titanium alloy for a time sufficient to form α

-phase precipitates within the binary β

-titanium alloy;

wherein after heating the binary β

-titanium alloy in the hot worked condition at the aging temperature, the binary β

-titanium alloy has a tensile strength of at least 150 ksi and an elongation of at least 12 percent; and

wherein the binary β

-titanium alloy is not solution heat treated intermediate hot working the binary β

-titanium alloy and heating the binary β

-titanium alloy in the hot worked condition at the aging temperature.